One of the more jarring aspects of each new baseball season is seeing established stars wearing strange uniforms.

Player movement is very much a reality of today’s game, and eventually the strangeness wears off. We’re less than a month into the 2013 season, though, so it’s OK that some player/uniform combinations still seem disconcerting.

Here is a look at eight of those familiar faces in new places, along with a key number (stats are through Thursday) that highlights each player’s impact on his new team. Remember, the “small sample size” element is definitely in play this early in the season.

James Shields, Kansas City Royals

Even in his departure from the Tampa Bay Rays, Shields was the epitome of what that odds-defying franchise has become. He was a homegrown talent, a competitor with a mental toughness that matched his physical skills—Shields racked up six consecutive seasons of at least 200 innings but was traded to Kansas City when the cost of keeping him became prohibitive for the cost-conscious franchise. He was shipped, along with pitcher Wade Davis, to the Royals for two just-about-ready future stars, slugger Wil Myers and pitcher Jake Odorizzi (and a couple other prospects).

Number that matters: 3.56 (Shields’ strikeout-to-walk ratio)

The Royals have an outstanding core of young hitters, but their top pitching prospects have largely been a series of disappointments over the past few years. To compete for a postseason berth, they needed Shields to stabilize a rotation and set a strike-throwing example—they paid a high price in the trade—and he has done both so far. Shields has thrown at least six innings each of his five starts, and he recorded a complete game in his third start. Last season, Kansas City starters combined for just two complete games, and the best strikeout-to-walk ratio for anyone on the team—relievers included—was 3.67.

Torii Hunter, Detroit Tigers

Hunter might not have been the Los Angeles Angels’ single-best player during any of his five seasons with the franchise, but he was a consistent force in the middle of the lineup and was the heart and soul of the clubhouse. But he left the West Coast for middle America and a two-year, $26 million free-agent deal this past offseason.

Number that matters: 2 (Hunter’s spot in the batting order)

Last season, the spot in front of Miguel Cabrera was a revolving door of despair for manager Jim Leyland; he wrote eight different players’ names in the two-slot at least once. And despite the best hitter in baseball protecting them—Cabrera won the Triple Crown—those players managed an unacceptable .257/.313/.397 slash line. Hunter has thrived in that spot so far this season, rolling up a slash line of .373/.416/.518.

Shin-Soo Choo, Cincinnati Reds

The inability of Cincinnati’s leadoff men to get on base last season was almost comical, providing you weren’t a Reds fan, of course. Players in the No. 1 slot in the Cincinnati lineup hit just .208 and had an anemic .254 on-base percentage—the average on-base percentage in the majors (pitchers included) was .319 in 2012. So, yes, that inefficiency had to be addressed. Cincinnati landed Choo from the Cleveland Indians, with whom he had played the past seven seasons, as part of a three-team deal that also included the Arizona Diamondbacks.

Number that matters: .523 (Choo’s on-base percentage)

No, that isn’t a misprint. Choo has reached base at least twice in 17 of Cincinnati’s first 22 games; he is batting .378, has been hit by pitch 10 times and has drawn 15 walks. Reds leadoff hitters walked a total of 37 times and had just eight HBPs last season. Choo has been a perfect fit for Cincinnati.

Justin Upton and B.J. Upton, Atlanta Braves

The brothers Upton were both expected to leave their current teams last winter: B.J. was a free agent the Rays couldn’t afford to re-sign, and Justin was a superstar-in-waiting the Diamondbacks seemingly couldn’t wait to trade. That they both landed in Atlanta was a wonderful thing for the family, and it has been a shot in the arm for the NL East-leading Braves and the franchise’s fan base.

Number that counts: 3 (hits with runners in scoring position)

The brothers Upton have combined for 14 homers (Justin leads the majors with 11), but 13 of those have been solo shots, which is a big reason they have combined for just 21 RBIs. Through Atlanta’s first 21 games, the Uptons are 3-for-27 with runners in scoring position. Despite batting third in the order, Justin has just 10 at-bats with runners in scoring position (he has two hits), because B.J., the most common leadoff man, is hitting just .150. And Jason Heyward, the most common No. 2 hitter, was batting just .121 before he landed on the disabled list (appendectomy).

Josh Hamilton, Los Angeles Angels

A year after signing slugger Albert Pujols to a massive free-agent contract, the Angels inked Hamilton to an almost-as-massive free-agent contract. Hamilton became a superstar in his five years in Texas, winning the 2010 AL MVP Award and leading the Rangers to the World Series in back-to-back seasons. A five-year, $125 million deal convinced him to move from the Lone Star State to California.

Number that matters: .625 (Hamilton’s OPS)

This hasn’t been the start Hamilton hoped for in Anaheim. His OPS as a Ranger was a healthy .912, but Hamilton is streaky. In 2012, his OPS in July was .607, but .943 in August and .873 in September. Pujols also famously had a slow start to his Angels’ career (.510 OPS through his first 35 games, but a .964 OPS the rest of the season). For Hamilton, this too shall pass.

Mike Napoli, Boston Red Sox

After two years with the Rangers, Napoli’s offseason was tumultuous, to say the least. He originally agreed to a three-year deal with the Red Sox in early December, but a hip ailment that turned up during his physical led to an extended period of uncertainty before Napoli and the team finally finalized a one-year deal in mid-January.

Number that matters: 1.058 (Napoli’s OPS with runners in scoring position)

Napoli has been exactly what the Red Sox have needed—his 26 RBIs lead the majors. He also leads the majors with 11 doubles, and eight of those two-basers have come with at least one teammate on base.

Travis Hafner, New York Yankees

“Pronk” joined the Yankees on a low-risk deal (one year, $2 million) after 10 memorable (for good and not-so-good reasons) seasons in Cleveland. The transition into the Matt Stairs phase of his career—a lefthanded power hitter for hire who may or may not actually own a glove—has been a smooth one for Hafner, who doesn’t turn 36 until early June.

Number that matters: 5 (Hafner’s homers)

This is the first time Hafner has had this many homers in the season’s opening month since he hit five in April 2007. And those blasts, along with six from fellow new pinstriper Vernon Wells, have helped keep the Yankees afloat while they deal with early injury issues to Derek Jeter, Alex Rodriguez, Mark Teixeira and Curtis Granderson.